System of distribution.



PATENTED MAR; 31, 1908.

D. HALL.

SYSTEM OF DISTRIBUTION.

APPLIOATION FILED FEB. 7, 1906.

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David flall- EY I 54% ATTURNEY No. 883,195. PATENTED MAR. 31,1908.

D. HALL SYSTEM OF DISTRIBUTION.

APPLICATION rum) FEB. 7, 1906.

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Lg Q4 MTNESSES/ p id ,Jlallx f M BY 4 4 UNITED STA'IES PATENT OFFICE.

DAVID HALL,- OF NORWOOD, OHIO, ASSIGNOR TO THE BULLOCK ELECTRIC MANUFACTURING COMPANY, A CORPORATION OF OHIO.

SYSTEM OF DISTRIBUTION.

Specification of Letters Patent.

Patented March 31, 1908.

Application filed Februaryfi, 1906. Serial No. 299,863.

have invented certain new and useful Improvementsin Systems of Distribution, of which the following is a full, clear, and exact specification. i

My invention relates to multiple voltage systems of distribution having any number of feeder conductors and circuits, and particularly to three-wire systems in which the voltages between the main conductors and the compensating conductor are equal, called the symmetrical three-wire systems, or in which the voltages are unequal, called the unsymmetrical three-wire systems.

It is customary to employ in a multiplevoltage system a balancer, as it is commonly called in the-art, consisting of two or more dynamo-electric .mach-ines connected across the main conductors or legs of thesystem and to the neutral or compensating conductor or -conductors. As is well known, when the currents in the branches of the system are equal or balanced, said dynamoelectric machines run as motors without loadand with slight losses. become unequal, current fiows through one or more compensating conductors, and one or more of said machines are driven as generators to supply current to the branch or branches having the heavier current or currents to maintain the voltages at substan tially their proper values.

On account of they inherent regulating qualities of compound-wpund machines, it is desirable to employ compound wound dynamoelectric machines in the balancer.

set, in order that upon unbalancing of the currents the generator or generators of the balancer set may supply current at lncreased voltage as such unbalancing increases.

Since the current through the armature and series field winding of one of the machines of a balancer is in opposite directions when said machine is acting as a enerator and as a motor, and since the series and shunt fields of a machine must be cumulativewhen the machine acts as a generator, it follows that the fields are differential when the same mach" e acts as a motor. In other words, the machines actln as generators have cumnla- When said currents carrying the on account of its speed. q

my invention is to compounding action depends on thevalu'e of the current in the compensating conductor.

It is well known that a motor having 'differentially wound fields may race or run away on current overload. 'Heretofore on account of the differential action of the fields of the motor, compound-wound balancers have been unsuccessful when the unbalancing of the currents is considerable, because of their unstable action and the danger that the machines of the balancer will run away. When the currents in all the branches of the system are equal and all the machines are running as motors, the field of each machine is due chiefly to its shunt field winding. Now as the currents become une ual, the field of the motor due to the shunt eld winding is weakened by the current in the series field winding, which is 'now greater. than when the currents were equal. The result is that the speed of the motor is increased, increasing the voltage of the generator to which it is connected. Now if the difference in the currents becomes greater, the differential field action of the motor increases and its speed becomes correspondingly greater. The result is that the volta e Impressed upon the lamps or other trans ating devices on thebranch or branches greater currents becomes so great that San translating devices may be destroyed or the balancer may be destroyed One of theaobjectsof provide means whereby I may obtain the cumulative field action of the machine act-.

in as a generator without the differential fie (1 action of the machine acting as a mo- Q tor,whe re by the unsta'bleaction is avoided.

Ajfurther object is to provide means whereby two or more compound wound balancers may be operated in parallel on thesame system. In carrying out my invention, 1 provide a balancer which consists of compound-wound dynamo-electric machines which are con nected to the conductors of a multiple-voltage distributing system, and provide means for automatically cutting out of service one of. the field windings of one of said machines when the currentsin the branches of the system become unequal.

In another aspect, my invention consists in amultiple-voltage system o'f distribution having a balancer set inc uding dynammelectrio conductors orlegs of the three-wire distribmachines for supplyin the balancing current when the currents in t e branches of the system are unequal, each of said machines having afield winding in series with its armature and a field winding connected across the main conductors in shunt to the armature, and means responsive to a passage of current or areversal of current in a compensating conductor for automatically cutting out of service the series winding of the motor or machine connected to the compensating conductor on that side of the latter which carries the lesser current, in other words for changing such machine 'to a shunt motor, the generator or machine connected on the other side of said compensating conductor remaining compoundwound.

More specifically considered, my invention consists in a three wire system of distribution having two main conductors forming the legs of the system, and a compensatin balancing or neutral conductor, a plura ity of balancers connected in parallel across the legs of the system and to the compensating or balancing conductor, :each balancer comprising two dynamo-electric machines, the armatures of which are connected across the legs of the system, series windings for the sa d machines connected in circuit with the armatures, a shunt winding for each machine connected to the legs of the system, means for short-circuiting the series winding of the machines on either side of the compensating or balancing conductor, and means responsive to'the unbalancing of the currents in the two sides of the system for operatin said means to short-circuit the series win ings of those machines acting as motors.

My invention still further consists in the combinations and arrangements of parts described in the specification and set forth in the appended claims.

For a better understanding of myinvention, reference is had to the accompanying drawing, in which Figure 1 shows a portion of a three-wire distribu ting system having my invention a plied thereto; Fig. 2 is a perspective of t e preferred form of the reverse current relay employed in carrying out my invention; and Fig. 3 is a portion of a three wire distributing system having my invention applied thereto, two balancers being connected in parallel across the legs of the system;

Referring now to the figures of the drawing, I have shown at 10 a source of current, in this case a single generator. The main uting circuit are shownat 11 and 12, res ectively and the neutral, compensating or alancing conductor is shown at 13. The balancer set B, inFig. 1, consists of two dynamoelectric machines 1 4 and 1 5, having armatures 16 and 17, and series field windings 18 and F field winding, de

19, the two field windings 18 and 19 and the two armature windings being connected in series across the main conductors 11 and 12. The machines are also provided with shunt field windings 20 and 21, also connected across the conductors 11 and 12. The neutral, compensating or balancing conductor 13 is connected to a common connection of-thc two armatures 22, the-differences in potential between which andeither leg of the system is redetermined and may be equal or unequai depending on whether the system is a symmetrical or an unsymmetrical one. However, merely for ease of description, the system will be assumed below to be symmetrical. The armatures'of the two dynamo-electric machines are intended to be mechanically connected and will preferably be mounted on the same shaft so as to rotate in unison. In series with one of the shunt field windings 21, is the rheostat 23, by means of which the'relative values of current in the two shunt windings 20 and 21 can be adjusted. Translating devices, in this case's'hown current passing from the neutral conductor 13 through the motor armature 17, to conductor 12, and through the generator armature 14 to conductor 1], the motor driving the generator so as to supply currentto the translating device 24 in proportion to the difference in the loads, so as to maintain the voltages between the main conductors and the compensating conductor at the pro er values. When the loads are equal, the va He of thecurrent passing through the series fields and armatures is very small and hence the differential field action is not considerable. When, however, the loads become unbalanced the differential field action in the motor becomes much lar er, the eilect of the series field winding, which opposes the shunt ending upon the difference in the loads, and ence on the current flowing in the neutral or compensating conductor. As was explained above the differential field action might result in the translating devices between the conductors 11 and 13 being destroyed, or the apparatus itself wrecked on account of its speed. In order that I may avoid this differential field action in the motor of the balancer when the loads are unequal, I provide means for temporarily cutting out of service the series field winding of either machine'when it acts as a motor while the unbalanced condition of the loads continue, so as to change that machine from a compound-wound machine to a shunt wound machine, the generator of the balancer set remaining a compound-wound, machine and having cumulativefields. This I can accomplish referably b short-circuiting the series fiel winding of t at machine which acts as a motor when the loads are unbalanced, and by restoring said field winding when such lack of balance ceases. I may, however, instead of short-circuiting the series winding of the machine acting as -a motor, employ any other suitable means for rendering it inoperative or nullifying its effect, as opening its circuit entirely and providing another path for the armature current.

The short-circuiting devices consistchiefly of two solenoid switches 26 and 27, the former being employed for short-circuiting the series field winding 18 of the machine 14 on the one side of the system, and the latter for short-circuiting the series field Winding 19 of the machine on the other side of the system. Switch 26 has twostationary contacts 28 and 29 connected respectively by conductors 30 and 31 to the main conductor or leg 11, and to a point between the series field 18 and the armature 16 of machine 14.

These two contacts are adapted to be to be bridged and hence the short-circuit of field 19 completed by a bridging contact 39 connected to the core 40 of a solenoid having a coil 41. As is shown in Fi 1 the cores of the solenoidsare connected y a bar or rod 42, pivoted at 43. The object of this bar is to assure the closing of only a single switch at a time.

The solenoid switches 26 and 27 may be controlled in any suitable manner. In this case, a reverse current relay 44, shown in perspective in Fig. 2 is employed for that purpose. This relay consists of a rectangular soft iron core 45, having a series coil 46 in the neutral or compensating conductor 13 and two opposite poles 47 and 48, and a core 49 pivoted at 50 having three legs or poles 51, 52 and 53, and a potential coil 54 connected in this case across the compensating conductor 13 and leg 12 of the system. The movable member of the relay has a depending arm 55, having at its lower end two contact faces 56 and 57, adapted to bridge when thrown to the left, two sta are so bent that their ends are in the same of the core 45.

determined values. I through the conductor 13, coil 46 is enerplane and in the plane of the poles 47 and 48 Since the core 49 is rovided with the potential coil54, it will a ways he magnetized in the same direction, for the reason that the direction of the current through the coil is fixed. Core 44, however, is only energized when the loads are unbalanced and current flows along the 'compensating conductor 13, and the direction of the magnetic lines through the core and hence the polarity of the poles is determined by the direction of the current in the conductor 13.

When the loads on the two sides of the system are balanced and the core 45 is deenergized, the movable core 49 is held in its central or mid position by springs 62. When the core is energized in one direction, the movable core is attracted and moved in one direction and hence the depending arm bridges one pair of contacts 58 and 59, and when the coreis energized in the opposite direction the core is attracted in the opposite direction and hence the depending arm bridges the other pair of contacts 60 and 61.

Coil 34 of solenoid switch 26, is connected to conductor or leg 1], and to the relay contact 58, the other contact 59 of the pair being connected to the opposite leg 12. (oil 41 of solenoid switch 27 is connected to leg 11 and to relay contact 60, the other contact 61 of that pair being connected to leg 12. Thus when the circuit through either coil is completed, that coilis subjected to the full voltage of the system.

The operation will now be explained more in detail. When the loads on the two sides ofthe system are equal or balanced, there is no passage of current along the neutral or compensating conductor 13, and both machines 14 and 15 run at constant speed as motors with slight losses. With equal loads on both sides of the system, the core 45 is de-magnetized and the movable core 49 is held in its central or mid position by the s rings 62. When however, the loads on the two sides of the system become unequal, current flows along the compensating con ductor 1'3, and that machine of the balancer on the less heavily loaded side drives the machine on the more heavily loaded side as a generator to su ply the balancing current to the lamps or ot er translating devicesv and to maintain the difierences in potential between the conductor 13 and the two legs of the system at substantially their pre When current passes gized and core 45,is magnetized in one direction or the other, depending upon the direcdepending arm 55 bridges one pair of con Y tacts completing the circuit through one of the coils of the short-circuiting switches. The coil which is energized attracts its core, and the bridging contact connected thereto bridges one pair of contacts 28-29 or 35-36 and the short-circuit is completedaround one of the series coils 18 or 19 Assume by Way of example, that a greater load is between the conductors 11 and" 13 than between the conductors 13 and 12, and current passes alon the conductor 13 in the direction indicate by the dotted arrow above the conductor. The machine 15 of the balancer then drives machine 14 as a generator, which then sup lies currentto the more heavily loaded si e to an extent depending upon the difference in the loads to maintain the potential of the conductor 13 at the proper value relative to that of the conductors 1 1 and 12. If the coils of the re verse current relay are roperly wound and connected, the legs of the rrfovable core are moved to.the left and the de ending arm moved to the right so as to b and 61, closing the circuit of the coil 41 of the short-circuitin switch 27. Core 40 of the switch-is quic y moved u ward until the contacts 35-36 are bridged y the movable contact 39 completing the short-circuit through the conductors 37 and 38 around the series field coil'19. This motor, as is seen, has been converted from a compoundwound machine to a shunt motor while the generator 14 continues to be a compoundwound machine, its field windings being. cumulative. If the resistance of the conductors 3738 is sufficiently small very little current passes through theseries' field 19. The reverse current relay will remain in the position ust described and the field 19 will continue to be shunted by the conductors 37 and 38 as long as the load between conductors 11 and 1.3 is greater than the load between conductbrs 13 and 12, or until the loads become so near egual that the attraction between the poles o the cores of the relay is less than the pull of the sprin 62. By properly adjusting the springs 62 t e relay can be made to o erate at any desired value of current incon uctor 13 and hence at any desired unbalancing of the loads. This is an important feature for the reason that it may not be desired that the relay 0 erate until there is a certain predetermine difference inthe loads. If now, the loads are made equal, the movable member of the relay will return to ts mid osition. If the load on the opposite side 0 the system or between the conductors 13 and 12 becomes greater than between conductors 11 and 13, the movable member of the relay is moved in the opposite direction to that described above so as to close the switch 26 and to short-circuit the series coil 18 of the machine ]4. In this case, current asses along the balancing conductor 13 in t e direction indicated by the dotted arrow below conducridge contacts is slight, onl

tor 13. If the balancing current supplied b one or the other of the machines is insu cient, it can be increased to the desired amount by changing the relative resistances in the circuits of the shuntcoils 20 and 21, by means of the rheostat 23.

Under some circumstances, it ma be desired to have the difference in the oads on the two sides of the system considerable at certain periods, and again at other 'eriods, to have the difference in the loa s very slight. Although the time during which the loads are greatly unbalanced may be small, and at all other times the loads may be equal or only sli htly unbalanced, it is necessary to provide a alancer having machines of sufficient size to meet the requirements of the ex treme condition of theunbalancing of the loads. If only a single balancer is employed,

it will be necessary to drive at all times much larger machines than would ordinarily be necessary to su ply the balance of current. In order to re uce to a minimum the losses in operating a balancer when the difference in the unbalancing varies greatly at different times, I connect in parallel to the system a plurality of balancers, in this case two, of different sizes or capacities. When the unbalancin the smaller balancer set neec be employe to sup ly the balancing current, the larger balancer remaining idle. When however, the unbalancing of the loads becomesso great that the smaller set cannot supply sufiicient current to maintain the lamps or other translating devices on the more heavily loaded side at the proper voltage, the lar er set is brought into service and the smal er balancer is cut out. If the larger balancer set is unable to supply suflicient current, both machines are brought into service at the same time and operate on the same system in parallel.

If two ormore balancers, each consisting of two compound-wound dynamo-electric machines, are connected and operated in parallel on the same system, the dan er to the lamps and to the machines themse ves due to the difierential field action of the motors, when the loads are unbalanced, is greater than when a single balancer is em loyed. This is probably due to the fact that t 1e generator of the lar er balancer may, in case of increase of s eed of the lar er balancer over the smaller alancer, suppl v current to the generator of the smaller balancer, changing it to a motor and increasing the speed of that balancer. Thus the operation would be very unstable, the function as balancers would be lessened, and the danger to the lamps and machines would be increased. If the series fields are short-circuited there is less danger of the speed of one balancer becoming greater than the s eed of the other balancer. My

invention t erefore has a special utility when ductor.

' ancer B are provided respectively with series windings li and 19 and with shunt .windings 20 and 21 and the machines of balancer B are provided respectively with series windings 18 and 19 and with shunt windings 20 and 21 Machines 14 and 14* are connected by an equalizer 63, and machines 15? and 15 are connected by an equalizer 64. Two switches 26" and 27 are em ployed for short-circuiting the series windings of the machines, as in the case previously described. In this case,one switch and the conductors connected thereto short circuits the series windings of the two machines on one side of the compensating con- 26 are connected re'spectivel to the leg 11 and to the equalizer 63, which to the machines 14 and 14 at points between the series. field windings and the armatures, and the stationary contacts of switch 27 are connected res 'ectively to equalizer 64 and th the leg 12 o the distributing system. The switches in this case are not shown joined by a pivoted bar as shown in Fig. 1, though such a bar'may be used if desired. A reverse current relay 44 similar in all respects to the relay first described, completes the circuit through either solenoid coil of switches 26 and 27*when the loads are unbalanced, or when conductor 13 arrangement is ap licable without change to the unsymmetrica three wire system. In-

deed it is not limited to three wire sys-.

tems, for it may be applied with equal effect to a system havin more than three wires,

in which case the alancer'wouldv consist of more than two dynamo-electric machines.

Itis evident that many changes ma be made in the details and connections wit out-v 4 interfering with the main features of my invention. It is to be understood that all machines and conductors may be provided with The stationary contacts of switch is connected When v the necessary switches and circuit breakers commonly employed for convenient connection and disconnection. I aim in my claims to cover all modifications which do not involve a departure from the spirit and scope of my invention.

What I claim as new and desire to secure by LettersPatent is:-

1. In a multiple voltage system of distribution, more than two conductors, a balancer including a plurality of compoundwound dynamo-electric machines connected to said conductors, and means for automatically cutting out of service one of the field windin s of one of said machines when the ratio 0 the loads between the different conductors departs from normal.

'2. In a three-wire system of distribution, a

source of current, two main conductors, a neutral conductor, a balancer set including two compound-wound dynamo-electric machines connected to said co nductors and automatic means for cutting out one of the field windings of one of said dynamo-electric machines when the currents become unbalanced on the two sides of the system.

3. In a multi le voltage system of distribution, a lura ity offeeder conductors, aplurality 0 compound wound dynamo-electric machines connected to said conductors and adapted to act as motors or generators to sup ly current to the branch or branches of t e system which carry the heaviest currents to maintain the voltages at the proper values, and means for automatically short-circuitingthe series field of the machine which acts as a motor to drive another machine as a generator when the currents are unbalance 4. In a multiple voltage system of distribution, more than two feeder conductors, a

balancer consisting of a plurality of compound-wound dynamo-electric machine's mechanically connected together and electrically connected to the conductors of the system,

and automatic means for rendering ino erative the series field of that machine w ich drives another as a generator when the currents' become unbalanced.

5. In a multiple-voltage system of distribution, ore than two conductors, a balancer consisting of a plurality of compoundwound dynamo-electric machines connected to the conductors of the system, and automatic means for transforming that dynamo-machine. which-acts as a motor to drive another as a generator, from a compound-wound to a shunt wound dynamoequal.

6; In a multiple-voltage system of distribution, more than two conductors, a balelectric machine, when the currents are unv ancer consisting of a plurality of-compoundwound dynamo-electric 'machines connected I to said conductors, and means mcludmg a plurality of switches for automatically cutting out of service the series winding of any one of said machines when it acts as a motor to drive another as a generator when the ratio of the loads on the different branches of the system is other than normal.

7 In a three-wire system of distribution, a source of current, two main conductors, a neutral conductor, a balancer set including two dynamo-electric machines connected to the three conductors, series and shunt field windings for said machines and means whereby the series field winding of one of said machines will be cut out of service when the currents on the two sides of the neutral conductor become unbalanced. V

8. In a multiple-voltagesystem of distribution, a source of current, a plurality of conductors including two main conductors and a neutral or balancing conductor, a balancer set including two dynamo electric machines connected to said conductors for supplying the balancing current, said machines having series and shunt windings, and means for automatically short-circuiting the series winding of the machine on the branch carrying the smaller current when the cur-' rents in the branches become unbalanced.

-9. In a multiple-voltage system of distribution, a-source of current, a plurality of conductors including two main conductors and a neutral or balancing conductor, a balancer comprising two compound-wound dynamo-electric machines connected to said conductors for supplying the balancing current, and means responsive to an unbalancing of the currents for changing the machine on the branch having the smaller current from a compound-wound machine to a shunt wound machine.

10. In a multiple-voltage system of distribution, a plurality of feeder conductors including two main conductors and a compensating or neutral conductor, a balancer including two machines adapted to act as a generator and motor respectively when the currents'taken by the different circuits become une ual or unbalanced, series and shunt field windmg's for said machines, and means responsive to an unbalancing of the currents for short-circuiting the series winding of the machine actingas a motor.

11. In a three-wire system of distribution, two main conductors and a compensatin or neutral conductor, a balancer set inclu in two dynamo-electric machines each adapte to act as a motor or generator, depending on which side of the system has the greater current, and means responsive to arrunbalancing of the currents for automaticallfy cutting out of service the series winding 0 the machine then acting as a motor.

12. In a three-wire system of distribution, 1

two main conductors, a compensating or balancing conductor, a mam source of ourrent, a balancer set including two dynamoelectric machines adapted to act as motors or generators for supplylng. the balance of current when the currents are unequal, and

automatic means responsive to an unbalancing of the currents for short-circuiting the series winding of either machine when it becomes a motor.

13. In a three-wire system of distribution, two main conductors and a balancing or compensating conductor, a balancer comprising two dynamo-electric machines for supplying the balancing current when the currents are unequal, each of said machines having a series and a shunt-field winding, 30 and means responsive to a passage or reversal of current in the balancing or compensating conductor for cutting out of service the se ries winding of the motor of said balancer set.

14. In a three-wire system of distribution, two main conductors and a balancing or compensating conductor, a balancer set includmg two dynamo-electric machines for supplying the balancing current when the currents on the two sides of the system are unequal, each of said machines having awinding in series with its armature and a winding 'connected across the main conductors in shunt to the armature, and means responsive to a passage of current or reversal of current 111 the compensating or balancing conductor for automatically short-circuiting the series winding of the machine on the side' having the lesser current, and for connecting into clrcuit the series winding of the other machine. I

' 15. In a three-wire system of distribution, two main conductors and a balancing or compensating conductor, a balancer set includmg two dynamo-electric machines connected across the main conductors, and each connected to the balancing or compensating conductor, field windings in series with the armatures of said machines, a shunt winding for each machine connected across the main conductors, means including a pair of switches for short-circuiting said series windings, and means for controlhng said switches to shortcircuit the series winding of the motor of the balancer set when the currents on the two 5 sides of the system are unequal.

' 16. In a three-wire system of distribution, two main conductors forming the legs of the system and a compensatin or balancing conductor, a balancer set inc uding two dynamo-electric machines having armatures and series field windings connected across the legs of the system and connected at a central point of thecompensating conductor, a shunt eld winding for each machine connected across the legs of the system, means including a pair of switches for short-circuiting the series winding of either machine when acting as a motor, and means including areverse current relay having a coil connected to the compensating conductor for controlling theshort-circuiting switches.

17. In a multiple-voltage system of dis- 7 tribution, a plurality of conductors, a plu- Correction in Letters Patent No. 883,195.

rality of balancers connected in parallel to the conductors of said system, each of said balancers consisting of a plurality of compoundwound dynamo-electric machines, and automatic means for cutting outof service the series field windings of those machines which act as motors to drive other machines as generators to supply the balanciiig current when the currents are unequal.

18. In a three-wire system of distribution, two main conductors forming the legs of the system, and a compensating or balancing conductor, a plurality of b'alancers connected in parallel across the legs of the system and to the compensating or balancing conductor, each halancer comprising two dynamoelectrio machines having series and shunt field windings, and means for automatically cutting out of service the series winding of the machines of each set which become motors by the unbalancing of the currents.

record of the case in the Patent Office.

Signed and sealed this 28th day of April, A. 1)., i908.

19. In a three-wire system ofdistribution, two main conductors forming the legs of the system, and a compensating or balancing and means responsive to' an unbalancing of the currents for operating said means to shortcircuit the series windings of those machines acting as motors.

In testimony whereof I affix my signature, in the presence of two witnesses.

DAVID HALL. Witnesses ARTHUR F. Knors, FRED J. KINSEY.

It is hereby certified that in"Letters Patent No. 883,195, granted March 31, 1908, upon the application of David Hall, of Norwood, Ohio, for an improvement in Systems of Distribution, an error appears in the printed specification requiring correction, as follows In line 124, page 6, the word of should read to; and that the said Letters Patent should be read with thiscorrection therein that the same may conform-to the I O. C. BILLINGS,

Acting O'ommisssoner of Patents. 

